Image pickup apparatus

ABSTRACT

An image pickup apparatus is disclosed which prevents interference of a lens barrel with an optical member and so forth with certainty and is advantageous in achievement of reduction in scale, weight and cost of the optical member and an adapter ring. If it is detected by a detection section that an adapter ring is attached to an adapter ring attachment portion, then a lens barrel control section moves a lens barrel so that a front end of the lens barrel is positioned within a range rearwardly of a front end of the adapter ring. Since the front end of the lens barrel does not project forwardly of the front end of the adapter ring, the end of the lens barrel does not interfere with a conversion lens or the like attached to the front end of the adapter ring. It is not necessary to form the wide conversion lens or the adapter ring with an increased size in order to prevent the front end of the lens barrel positioned at its projecting position from interfering with a lens of the wide conversion lens.

BACKGROUND OF THE INVENTION

This invention relates to an image pickup apparatus.

Image pickup apparatus of the retractable barrel type are availablewherein a lens barrel in which an image pickup optical system isaccommodated is movable between a projecting position in which itprojects forwardly of a casing and an accommodated position in which itis accommodated in the casing.

In some of conventional image pickup apparatus of the type described, inorder to allow an optical member such as a conversion lens or a filterto be located forwardly of an image pickup optical system, an adapterring formed in a cylindrical wall shape is removably attached to athreaded portion provided annularly on a front face of the casing suchthat it surrounds the lens barrel. The optical member is removablyattached to a front end of the adapter ring. One of the image pickupapparatus of the type just described is disclosed, for example, inJapanese Patent No. 3174205 (hereinafter referred to as Patent Document1).

Another one of the image pickup apparatus of the type described above isdisclosed, for example, in Japanese Patent Laid-open No. Hei 10-48737(hereinafter referred to as Patent Document 2). In the image pickupapparatus, an optical member including an adapter for three-dimensionalimage pickup is removably attached to a front end of a lens barrel, anda detection switch which exhibits an on state when the optical member isattached to the lens barrel is provided at a front end of the lensbarrel. The image pickup apparatus records identification data on a filmbased on the operation of the detection switch.

In the image pickup apparatus of the Patent Document 1, the image pickupoptical system is formed from a zoom lens, and the projection amount ofthe lens barrel varies in response to the zooming operation. Where it istaken into consideration to attach an optical member to the adapterring, when the lens barrel is positioned at the most projectingposition, the front end of the lens barrel must not interfere with theoptical member attached to the adapter ring.

Therefore, in order to assure the distance between the optical memberand the front end of the lens barrel, it is necessary to form theadapter ring and the optical member with great dimensions in thedirection of the optical axis of them. Further, in order to preventappearance of an eclipse with the image pickup optical system, also thedimension in a diametrical direction of the adapter ring and the opticalmember must be set great. Accordingly, the image pickup apparatus of thePatent Document 1 is disadvantageous in that increase in scale, weightand cost of the adapter ring and the optical member cannot be avoided.

Meanwhile, although the image pickup apparatus of the Patent Document 2detects attachment of an optical member to the lens barrel and performspredetermined control, the Patent Document 2 is silent of interferenceof the front end of the retractable lens barrel with the optical memberattached to the adapter ring.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image pickupapparatus which prevents interference of a lens barrel with an opticalmember and so forth with certainty and is advantageous in achievement ofreduction in scale, weight and cost of the optical member and an adapterring.

According to an aspect of the present invention, there is provided animage pickup apparatus of a retractable lens barrel type, including:

a casing;

a lens barrel provided on the casing and having an image pickup opticalsystem accommodated therein;

the lens barrel being movable between a projecting position in which thelens barrel projects most forwardly of the casing and an accommodatedposition in which the lens barrel is accommodated within the casing;

an annular adapter ring attachment portion provided on the casing insuch a manner as to surround the lens barrel;

detection means for detecting that an adapter ring is attached to theadapter ring attachment portion; and

lens barrel control means for controlling the projection amount of thelens barrel in response to a result of the detection of the detectionmeans;

the control of the projection amount of the lens barrel by the lensbarrel control means being performed within a range within which a frontend of the lens barrel is positioned rearwardly of a front end of theadapter ring while the adapter ring is attached to the adapter ringattachment portion.

In the image pickup apparatus, if it is detected by the detection meansthat an adapter ring is attached to the adapter ring attachment portion,then the lens barrel control means moves the lens barrel so that thefront end of the lens barrel is positioned rearwardly of the front endof the adapter ring. Accordingly, the front end of the lens barrel doesnot project forwardly of the front end of the adapter ring, andconsequently, the end of the lens barrel never interferes with anoptical member or the like attached to the front end of the adapterring.

Consequently, with the image pickup apparatus, the lens barrel can beprevented from interfering with an optical member such as a conversionlens with certainty while reduction in scale, weight and cost of theoptical member and the adapter ring can be achieved readily.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description and theappended claims, taken in conjunction with the accompanying drawings inwhich like parts or elements denoted by like reference symbols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a digital still camera to which thepresent invention is applied as viewed from obliquely forwardly;

FIG. 2 is a side elevational view of the digital still camera of FIG. 1;

FIG. 3 is a side elevational view of the digital still camera of FIG. 1,an adapter ring and a wide conversion lens;

FIG. 4 is a sectional view of the adapter ring and the wide conversionlens shown in FIG. 2;

FIG. 5 is a block diagram showing a configuration of a control systemfor controlling a retraction movement of a lens barrel of the digitalstill camera of FIG. 1;

FIG. 6 is a sectional view of the adapter ring shown in FIG. 3 and atele conversion lens; and

FIG. 7 is a schematic view showing a modified detection mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be describedin detail with reference to the accompanying drawings.

Referring first to FIGS. 1 and 2, there is shown a digital still camerato which the present invention is applied. The digital still camera 10is an image pickup apparatus and includes a casing 12, a lens barrel 14,an adapter ring attachment portion 16, an adapter ring 18 (FIG. 3), adetection section 20 (FIG. 5), and a lens barrel control section 22(FIG. 5).

Referring particularly to FIG. 1, a dial switch 1202 for changing overan image pickup mode, a shutter switch 1204 for triggering an imagepickup operation and a flash apparatus 1206 for illuminating auxiliarylight upon an image pickup subject are provided on an upper face of thecasing 12.

Referring now to FIG. 2, a display apparatus 1208 which may be a liquidcrystal display unit for displaying various data such as image data andcharacter data, a finder window 1210 for visually observing an imagepickup subject therethrough, a zooming operation switch 1211 forperforming a zooming operation of an image pickup optical system 15, apower supply switch (not shown) and so forth are provided on a rear faceof the casing 12.

Referring to FIGS. 1 and 2, the adapter ring attachment portion 16 isformed annularly such that it is swollen forwardly at a central portionof the front face of the casing 12. The lens barrel 14 is disposed onthe inner side of the adapter ring attachment portion 16.

In the present embodiment, the lens barrel 14 is formed as a two-stagetype lens barrel which includes a first lens barrel 1402 and a secondlens barrel 1404 incorporated for relative movement on the inner side ofthe first lens barrel 1402 as seen in FIG. 2. The image pickup opticalsystem 15 is accommodated in the lens barrels 1402 and 1404. An imagepickup element (not shown) for picking up an image of an image pickupsubject introduced by the image pickup optical system 15 to produce animage pickup signal is incorporated in the casing 12.

In the present embodiment, the image pickup optical system 15 is formedfrom a zoom lens, and the zooming ratio, that is, the image pickupmagnification or the focal length, can be varied by moving a lens whichforms the zoom lens in the direction of an optical axis of the zoomlens.

The lens barrel 14 is formed as of a so-called retractable type whereinit can be retracted by a lens barrel driving mechanism 24 (FIG. 5). Thelens barrel 14 is configured such that the projection amount thereofvaries in response to the zooming ratio of the image pickup opticalsystem 15, and is movable between a projecting position P1 in which theimage pickup optical system 15 is positioned at the most tele sideposition and the projection amount of the lens barrel 14 is maximum, andan accommodated position P0 in which the lens barrel 14 is accommodatedin the casing 12. Further, where the image pickup optical system 15 isset to the most wide angle side, the lens barrel 14 is positioned at anintermediate position P2 which is a position between the projectingposition P1 and the accommodated position P0 and forwardly of theadapter ring attachment portion 16.

Referring to FIG. 2, the adapter ring attachment portion 16 includes acylindrical wall portion 1602 which surrounds an outer circumferentialface of the lens barrel 14 with a space left therebetween, and a firstfemale screw 1604 formed on an inner circumferential face of thecylindrical wall portion 1602.

An annular stepped portion 1606 (FIG. 4) is formed at a location of theinner circumferential face of the cylindrical wall portion 1602 rathernear to the casing 12 such that it projects diametrically inwardlyfarther than the first female screw 1604.

Referring to FIGS. 3 and 4, the adapter ring 18 is formed in acylindrical wall shape having an inner diameter greater than the outerdiameter of the lens barrel 14.

A first male screw 1802 (rear end attaching portion) for screwingengagement with the first female screw 1604 of the adapter ringattachment portion 16 is formed at a rear end portion of the adapterring 18 such that the rear end portion of the adapter ring 18 isremovably attached to the adapter ring attachment portion 16 by screwingthe first male screw 1802 with the first female screw 1604.

A second female screw 1804 of an inner diameter greater than the outerdiameter of the first male screw 1802 is formed at a front end portionof the adapter ring 18. The second female screw 1804 is formed so as tobe screwed on a male screw 3002 of a wide conversion lens 30 as anoptical member such that the front end portion of the adapter ring 18 isremovably attached to the wide conversion lens 30 by screwing the secondfemale screw 1804 with the male screw 3002. In the present embodiment,an optical member attachment portion is formed from the second femalescrew 1804. In the present embodiment, the first female screw 1604 andthe first male screw 1802 are formed from double threaded screws whilethe second female screw 1804 is formed from a single threaded screw.

The adapter ring 18 is formed such that, where the rear end portionthereof is attached to the adapter ring attachment portion 16, the frontend of the adapter ring 18 is positioned rearwardly of the projectingposition P1 of the lens barrel 14.

Further, in the present embodiment, the adapter ring 18 is formed suchthat, where the rear end portion thereof is attached to the adapter ringattachment, portion 16, the front end of the adapter ring 18 ispositioned forwardly of the intermediate position P2 of the lens barrel14.

Furthermore, in the present embodiment, the adapter ring 18 is formedsuch that, where the rear end portion thereof is attached to the adapterring attachment portion 16 and the zooming ratio of the image pickupoptical system 15 is set to the most wide angle side, no eclipse occurswith the image pickup optical system 15. Also the inner diameter of thesecond female screw 1804 at the front end portion of the adapter ring 18is set to a value with which no eclipse occurs with the image pickupoptical system 15.

Referring to FIG. 4, the wide conversion lens 30 has an optical systemwhich includes one or more lenses 3006 for reducing, when it is attachedto the adapter ring attachment portion 16 through the adapter ring 18,the focal length of the image pickup optical system 15 to change thezooming ratio (angle of view) to the wide angle side. In FIG. 4,reference numeral 3004 denotes a fancy ring.

The detection section 20 detects that the adapter ring 18 is attached tothe adapter ring attachment portion 16. The detection section 20includes a movable pin 2002 disposed on the stepped portion 1606 of theadapter ring attachment portion 16 and a detection switch 2004 fordetecting a motion of the movable pin 2002.

The movable pin 2002 is provided for retraction movement on the steppedportion 1606 and is normally biased such that the front end thereofprojects forwardly from the stepped portion 1606.

The detection switch 2004 detects a motion of the movable pin 2002 andoutputs a detection signal in the form of an on/off signal to the lensbarrel control section 22. In particular, if the adapter ring 18 isattached to the adapter ring attachment portion 16, then the movable pin2002 is pushed by a rear end portion 1806 of the adapter ring 18 andmoved from the projecting position to a retracted position, and thedetection switch 2004 detects the motion of the movable pin 2002 andoutputs a corresponding detection signal.

Referring to FIG. 5, the lens barrel control section 22 controls thelens barrel driving mechanism 24 based on a zooming operation signalsupplied thereto from the zooming operation switch 1211 and a detectionsignal supplied thereto from the detection switch 2004 to control theprojection amount of the lens barrel 14.

In particular, the lens barrel control section 22 controls theprojection amount of the lens barrel 14 so that, when the power supplyswitch is turned off, the lens barrel 14 is positioned at theaccommodated position P0, but when the power supply switch is turned on,the lens barrel 14 is positioned at the intermediate position P2.

The lens barrel control section 22 is formed from, for example, amicrocomputer including a ROM for storing a control program, a RAM forproviding a working area, an interface for controlling communication ofa signal with the power supply switch, zooming operation switch 1211,detection switch 2004 and lens barrel driving mechanism 24, and a CPUfor executing the control program of the ROM to execute a controllingoperation.

Subsequently, operation when the digital still camera 10 is used to pickup an image is described.

First, operation when the digital still camera 10 is used solely, thatis, when the digital still camera 10 is used without the adapter ring 18or the wide conversion lens 30 attached thereto, is described.

When the power supply switch is in an off state, since the lens barrel14 is positioned at the accommodated position P0 and accommodated withinthe casing 12, the lens barrel 14 is prevented from interfering with anarticle outside the casing 12 and being acted upon by excessive force.

As described hereinabove, the movable pin 2002 is biased to the positionat which the front end portion thereof projects from the stepped portion1606.

If the power supply switch is turned on, then a detection signalrepresenting that the adapter ring 18 is not attached is supplied fromthe detection switch 2004 to the lens barrel control section 22.Consequently, the lens barrel control section 22 controls the lensbarrel driving mechanism 24 to move the lens barrel 14 to theintermediate position P2 at which image pickup can be performed. In thisstate, the user would visually observe the finder window 1210 or thedisplay apparatus 1208 and operate the zooming operation switch 1211 sothat a desired zooming ratio may be obtained. In response to anoperation signal of the zooming operation switch 1211 then, the lensbarrel control section 22 controls the lens barrel driving mechanism 24to move the lens barrel 14 between the intermediate position P2 and theprojecting position P1.

Then, the user would depress the shutter switch 1204 to perform imagepickup.

Now, operation when the digital still camera 10 is used with the adapterring 18 and the wide conversion lens 30 attached thereto is described.

First, the male screw 3002 of the wide conversion lens 30 would bescrewed into the second female screw 1804 of the adapter ring 18 toattach the wide conversion lens 30 to the front end portion of theadapter ring 18 as seen in FIG. 3.

Then, while the power supply switch of the digital still camera 10 is inan off state and the lens barrel 14 is positioned at the accommodatedposition P0, the first male screw 1802 of the adapter ring 18 would bescrewed into the first female screw 1604 of the adapter ring attachmentportion 16 as seen in FIG. 4. Consequently, the wide conversion lens 30and the adapter ring 18 are attached to the adapter ring attachmentportion 16.

In this instance, as the first male screw 1802 is screwed into the firstfemale screw 1604, the rear end portion 1806 of the adapter ring 18contacts with the front end of the movable pin 2002 to place and thenkeep the movable pin 2002 into and in the state retracted in the steppedportion 1606 as seen in FIG. 4.

Then, if the power supply switch is turned on, then a detection signalrepresenting that the adapter ring 18 is attached is supplied from thedetection switch 2004 to the lens barrel control section 22.Consequently, the lens barrel control section 22 controls the lensbarrel driving mechanism 24 to move the lens barrel 14 so that the frontend of the lens barrel 14 may be positioned within a range rearwardly ofthe front end of the adapter ring 18. In the present embodiment, thecontrol of the projection amount of the lens barrel 14 by the lensbarrel control section 22 is performed so that the projection amount ofthe lens barrel 14 with which the zooming ratio of the image pickupoptical system 15 exhibits the most wide angle side value may beobtained. Through the control of the projection amount, the lens barrel14 is moved to the intermediate position P2, and then the position ofthe lens barrel 14 is fixed at the intermediate position P2 and azooming movement is inhibited.

In particular, the projection amount of the lens barrel 14 by the lensbarrel control section 22 is controlled within a range within which thefront end of the lens barrel 14 is positioned rearwardly of the frontend of the adapter ring 18 while the adapter ring 18 is attached to theadapter ring attachment portion 16. Accordingly, the front end of thelens barrel 14 does not interfere with the lens 3006 of the wideconversion lens 30.

Consequently, the zooming ratio of the image pickup optical system 15 isfurther changed to the wide angle side by an action of the opticalsystem of the wide conversion lens 30.

Image pickup is performed by the user depressing the shutter switch 1204while observing the finder window 1210 or the display apparatus 1208.

It is to be noted that, in the present embodiment, even if the zoomingoperation switch 1211 is operated in this state, since the lens barrelcontrol section 22 inhibits a zooming operation, the position of thelens barrel 14 remains fixed at the intermediate position P2.

According to the digital still camera 10 having the configurationdescribed above, since control of the projection amount of the lensbarrel 14 by the lens barrel control section 22 is performed within therange within which the front end of the lens barrel 14 is positionedrearwardly of the front end of the adapter ring 18 while the adapterring 18 is attached to the adapter ring attachment portion 16, the frontend of the lens barrel 14 never interferes with such an optical memberas the lens 3006 of the wide conversion lens 30 attached to the frontend of the adapter ring 18.

Further, different from an alternative case wherein the front end of thelens barrel 14 positioned at the projecting position P1 is preventedfrom interfering with such an optical member as the wide conversion lens30, there is no necessity to increase the dimensions in the direction ofthe optical axis and the diametrical direction of the optical member andthe adapter ring 18.

Accordingly, while interference of the lens barrel 14 with the opticalmember is prevented with certainty, reduction in scale, weight and costof the optical member and the adapter ring 18 can be achievedadvantageously.

Further, since the optical member and the adapter ring 18 are reduced inscale in this manner, the digital still camera 10 is advantageous alsoin that handling of the digital still camera 10 in carrying or placingthe same while the optical member and the adapter ring 18 are attachedthereto is facilitated.

Further, in the present embodiment, the first female screw 1604 of theadapter ring attachment portion 16 and the first male screw 1802 of theadapter ring 18 are formed from double threaded screws while the secondfemale screw 1804 of the adapter ring 18 is formed from a singlethreaded screw. Accordingly, even if the outer diameter of the malescrew 3002 of the wide conversion lens 30 and the inner diameter of thefirst female screw 1604 of the adapter ring attachment portion 16 shouldbe equal to each other, since the male screw 3002 of the wide conversionlens 30 is a single threaded screw and the first female screw 1604 is adouble threaded screw, the male screw 3002 can be prevented from beingscrewed into the first female screw 1604 with certainty. Therefore, sucha situation that the wide conversion lens 30 is attached directly to theadapter ring attachment portion 16 in error and the front end of thelens barrel 14 interferes with the lens 3006 of the wide conversion lens30 can be prevented with certainty.

Further, if the pitch of the double threaded screws is set to equal toor less than ⅔ that of the single threaded screw, for example, with theformer set to 0.4 and with the latter set to 0.75, then the pitch of thedouble threaded screws is much different from the pitch of the singlethreaded screw. This makes it further difficult to screw the singlethreaded screw with the double threaded screw, and the male screw 3002can be prevented from being screwed into the first female screw 1604with a higher degree of certainty.

Further, if the modules of the second female screw 1804 of the adapterring 18 and the first female screw 1604 of the adapter ring attachmentportion 16 are set to different values from each other such that, forexample, the former is set to M46 and the latter is set to M45.5, thenthe male screw 3002 can be prevented from being screwed into the firstfemale screw 1604 with a higher degree of certainty.

Further, if the outer diameter of the second female screw 1804 of theadapter ring 18 is set to a dimension equal to that of the outerdiameter of a screw of a general filter or conversion lens and the outerdiameter of the first female screw 1604 of the lens barrel 14 is set toa dimension different from the dimension of the outer diameter of thesecond female screw 1804 described above, then the male screw 3002 canbe prevented from being screwed into the first female screw 1604 with ahigher degree of certainty.

Further, even if the digital still camera 10 is used while the adapterring 18 is attached to the adapter ring attachment portion 16 and nooptical member is attached to the adapter ring 18, since the front endof the lens barrel 14 is positioned rearwardly of the front end of theadapter ring 18, the front end of the lens barrel 14 is protected by theadapter ring 18. Consequently, such a situation that some articlecollides with the front end of the lens barrel 14 to damage the lensbarrel 14 or the lens barrel driving mechanism 24 can be preventedadvantageously.

It is to be noted that, while, in the present embodiment, the lensbarrel 14 is fixed at the intermediate position P2 to prevent a zoomingoperation while the adapter ring 18 is attached to the adapter ringattachment portion 16, only it is necessary to control the projectionamount of the lens barrel 14 by means of the lens barrel control section22 within the range within which the front end of the lens barrel 14 ispositioned rearwardly of the front end of the adapter ring 18. Thus, thelens barrel 14 may be moved within the range to perform a zoomingoperation.

Now, a second embodiment of the present invention is described.

FIG. 6 shows an adapter ring and a tele conversion lens of a digitalcamera as an image pickup apparatus according to the second embodimentof the present invention. The image pickup apparatus of the presentembodiment is a modification to but is different from the image pickupapparatus of the first described above only in the adapter ring and thetele conversion lens, and description is given below only of thedifferent members.

Referring to FIG. 6, according to the second embodiment, a teleconversion lens 32 as a conversion lens and an adapter ring 19 for thetele conversion lens 32 are attached to the digital still camera 10.

The adapter ring 19 is formed in a cylindrical wall shape having aninner diameter greater than the outer diameter of the lens barrel 14.

A first male screw 1902 for being screwed into the first female screw1604 of the adapter ring attachment portion 16 is formed at a rear endportion of the adapter ring 19 such that the rear end portion of theadapter ring 19 is removably attached to the adapter ring attachmentportion 16 by screwing the first male screw 1902 into the first femalescrew 1604.

The adapter ring 19 is configured such that, where the rear end portionthereof is attached to the adapter ring attachment portion 16, the frontend of the adapter ring 19 is positioned forwardly of the projectingposition P1 of the lens barrel 14.

Further, even if the adapter ring 19 is attached to the adapter ringattachment portion 16, a rear end portion 1906 of the adapter ring 19does not interfere with the movable pin 2002.

Accordingly, even if the adapter ring 19 is attached to the adapter ringattachment portion 16, the detection switch 2004 does not supply adetection signal indicating that the adapter ring 19 is attached to thelens barrel control section 22.

A second female screw 1904 having an inner diameter greater than theouter diameter of the first male screw 1902 is formed on a front endportion of the adapter ring 19. The second female screw 1904 is formedso as to be screwed with a male screw 3202 of the tele conversion lens32 such that the tele conversion lens 32 is removably attached to thefront end of the adapter ring 19 by screwing the second female screw1904 and the male screw 3202 with each other. In the present embodiment,an optical member attachment portion is formed from the second femalescrew 1904. Further, in the present embodiment, the first female screw1604 and the first male screw 1902 are formed from double threadedscrews while the second female screw 1904 is formed from a singlethreaded screw.

The tele conversion lens 32 includes an optical system which in turnincludes one or more lenses 3206 for extending, when it is attached tothe adapter ring attachment portion 16 through the adapter ring 19, thefocal length of the image pickup optical system 15 to change the zoomingratio (angle of view) to the tele side. In FIG. 6, reference numeral3204 denotes a fancy ring.

Now, operation when the digital still camera 10 is used with the adapterring 19 and the tele conversion lens 32 attached thereto is described.

First, the male screw 3202 of the tele conversion lens 32 would bescrewed into the second female screw 1904 of the adapter ring 19 toattach the tele conversion lens 32 to the front end of the adapter ring19 as seen in FIG. 6.

Then, while the power supply switch of the digital still camera 10 is inan off state and the lens barrel 14 is positioned at the accommodatedposition P0, the first male screw 1902 of the adapter ring 19 would bescrewed into the first female screw 1604 of the adapter ring attachmentportion 16. Consequently, the tele conversion lens 32 and the adapterring 19 are attached to the adapter ring attachment portion 16.

Thereupon, even if the first male screw 1902 is screwed into the firstfemale screw 1604, the rear end portion 1906 of the adapter ring 19 doesnot contact with the front end of the movable pin 2002.

Then, if the power supply switch is turned on, then a detection signalrepresenting that the adapter ring 19 is attached is supplied from thedetection switch 2004 to the lens barrel control section 22.Consequently, the lens barrel control section 22 performs a zoomingoperation of moving the lens barrel 14 between the intermediate positionP2 and the projecting position P1 similarly as in the case wherein thedigital still camera 10 is used solely.

Thereupon, even if the front end of the lens barrel 14 moves to theprojecting position P1 while the adapter ring 19 is attached to theadapter ring attachment portion 16, since the front end of the adapterring 19 is positioned forwardly of the projecting position P1 of thelens barrel 14, the front end of the lens barrel 14 does not interferewith the lens 3206 of the tele conversion lens 32.

Consequently, the zooming ratio of the image pickup optical system 15 isfurther changed to the tele side by an action of the optical system ofthe tele conversion lens 32.

Image photograph is performed by the user depressing the shutter switch1204 while visually observing the finder window 1210 or the displayapparatus 1208.

According to the digital still camera 10 having the configurationdescribed above, eve if the front end of the lens barrel 14 moves to theprojecting position P1 while the adapter ring 19 is attached to theadapter ring attachment portion 16, since the front end of the adapterring 19 is positioned forwardly of the projecting position P1 of thelens barrel 14, the front end of the lens barrel 14 does not interferewith the lens 3206 of the tele conversion lens 32 at all.

Accordingly, the lens barrel 14 can be prevented from interfering withthe tele conversion lens 32 with certainty.

Also in the present embodiment, where the male screw 3202 of the teleconversion lens 32 and the first female screw 1604 are formed as asingle threaded screw and a double threaded screw, respectively, orwhere the two screws are formed with different pitches from each other,with different modules from each other or with different diameters fromeach other, such a disadvantageous situation that the tele conversionlens 32 is attached directly to the adapter ring attachment portion 16in error and the front end of the lens barrel 14 interferes with thelens 3206 of the tele conversion lens 32 can be prevented withcertainty.

It is to be noted that, while, in the embodiments described above, theimage pickup optical system 15 is formed from a zoom lens, naturally thepresent invention can be applied also where the image pickup opticalsystem 15 has a fixed focal length or a fixed angle of view.

Further, while, in the embodiments described above, whether or not theadapter ring 18 is attached to the adapter ring attachment portion 16 isdetected based on whether or not the movable pin 2002 of the detectionsection 20 is pushed and the lens barrel control section 22 controls theprojection amount of the lens barrel 14 in response to a result of thedetection, the embodiment may be modified in the following manner.

For example, as seen in FIG. 7, first, second and third movable pins2202A, 2202B and 2202C are provided at the stepped portion 1606 of theadapter ring attachment portion 16 such that portions thereof projectingfrom the stepped portion 1606 have lengths different from one another,and different detection switches (not shown) from one another areprovided corresponding to the first, second and third movable pins2202A, 2202B and 2202C.

Three different first, second and third adapter rings are prepared forthe adapter ring 18.

The first adapter ring 18 is dimensioned such that it pushes only thefirst movable pin 2202A when the first male screw 1806 is screwed in thefirst female screw 1604.

The second adapter ring 18 is dimensioned such that it pushes the twofirst and second movable pins 2202A and 2202B while the first male screw1806 is screwed in the first female screw 1604.

The third adapter ring 18 is dimensioned such that it pushes all of thethree first, second and third movable pins 2202A, 2202B and 2202C whilethe first male screw 1806 is screwed in the first female screw 1604.

Where the configuration just described is employed, which one of thefirst, second and third adapters is attached to the adapter ringattachment portion 16 can be discriminated based on the states ofdetection signals outputted from the detection switches. Thus, theprojection amount of the lens barrel 14 can be controlled suitably foreach of the adapter rings based on a result of the discrimination.

Accordingly, while conversion lenses having different magnificationsfrom one another are attached to the first, second and third adapterrings and one of the adapter rings is attached to the adapter ringattachment portion 16, the projection amount of the lens barrel 14 canbe controlled by the lens barrel control section 22 so that the frontend of the lens barrel 14 may not interfere with the conversion lens.

It is to be noted that, while, in the embodiments described above, theimage pickup apparatus of the present invention is formed as the digitalstill camera 10, naturally the present invention can be applied tovarious image pickup apparatus such as a video camera.

While preferred embodiments of the present invention have been describedusing specific terms, such description is for illustrative purposesonly, and it is to be understood that changes and variations may be madewithout departing from the spirit or scope of the following claims.

1. An image pickup apparatus of a retractable lens barrel type,comprising: a casing; a lens barrel provided on said casing and havingan image pickup optical system accommodated therein; said lens barrelbeing movable between a projecting position in which said lens barrelprojects most forwardly of said casing and an accommodated position inwhich said lens barrel is accommodated within said casing; an annularadapter ring attachment portion provided on said casing in such a manneras to surround said lens barrel; detection means for detecting that anadapter ring is attached to said adapter ring attachment portion; andlens barrel control means for controlling the projection amount of saidlens barrel in response to a result of the detection of said detectionmeans; the control of the projection amount of said lens barrel by saidlens barrel control means being performed within a range within which afront end of said lens barrel is positioned rearwardly of a front end ofthe adapter ring while the adapter ring is attached to said adapter ringattachment portion.
 2. An image pickup apparatus according to claim 1,wherein said adapter ring attachment portion is formed from a firstfemale screw while a rear end attachment portion to which said adapterring attachment portion is attached is formed at a rear end portion ofsaid adapter ring, and an optical member attachment portion to which anoptical member such as a conversion lens or a filter is to be attachedis formed at a front end portion of the adapter ring, said rear endattachment portion being formed from a first male screw for beingscrewed into said first female screw, said optical member attachmentportion being formed from a second female screw for being screwed with athreaded portion of the optical member such as a conversion lens or afilter, said first female screw and said first male screw being formedfrom double threaded screws while said second female screw is formedfrom a single threaded screw.
 3. An image pickup apparatus according toclaim 1, wherein, where the adapter ring is attached to said adapterring attachment portion, the front end of the adapter ring is positionedrearwardly of the projected position of said lens barrel.
 4. An imagepickup apparatus according to claim 1, wherein said image pickup opticalsystem is formed from a zoom lens and said lens barrel is controlled sothat the projection amount of said lens barrel is varied in response toa zooming ratio of said image pickup optical system, the projectionamount of said lens barrel being controlled by said lens barrel controlmeans so that said lens barrel projects with a projection amount withwhich the zooming ratio of said image pickup optical system exhibits themost wide angle side value while the adapter ring is attached to saidadapter ring attachment portion.
 5. An image pickup apparatus accordingto claim 1, wherein said image pickup optical system is formed from azoom lens and the adapter ring is configured such that, where theadapter ring is attached to said adapter ring attachment portion and thezooming ratio of said image pickup optical system exhibits the most wideangle side value, said image pickup optical system does not suffer froman eclipse.
 6. An image pickup apparatus according to claim 1, whereinsaid conversion lens is a wide conversion lens which changes the angleof view of said image pickup optical system to the wide angle side.